1. Field of the Invention
This invention relates to imageable elements, and more particularly, imageable elements that require no post-exposure development step.
2. Discussion of the Art
Printing plates are typically prepared by imagewise exposing a layer of photosensitive material that has been coated on a substrate, and then removing either the exposed or unexposed portion of the layer, i.e., wash-off development of the layer with an organic or aqueous solvent. Both organic solvents and aqueous solvents have certain shortcomings with respect to environmental pollution. Organic solvents normally used as developers are volatile, toxic, and present pollution control and waste disposal problems. Aqueous solvents normally used as developers generally have a high pH, pick up waste materials from the plate, and, consequently, also present waste disposal problems. Furthermore, development by means of a solvent is time-consuming, e.g., often on the order of five to ten minutes. Finally, development by means of a solvent requires an additional process step.
In view of the foregoing shortcomings of wash-off development, it would be desirable to provide an imageable element that dispenses with a development step that requires the use of solvents.
A recording medium sensitive to light radiation of a predetermined wavelength is described in WIPO International Publication No. WO 88103667. The recording medium comprises an energy absorbing dye and an explosive metal azide complex having an appropriate temperature of explosive decomposition. The medium can be used in optical recording and is capable of emitting significant amounts of energy on explosive decomposition. The energy from explosive decomposition causes the formation of optically detectable pits in the recording medium.